God's demonstration of his own "righteousness" in the gospel, by which his justification of sinners is itself justified, presupposes a traditional doctrine that has fallen on hard times of late: the Foedus Operum, or, the "Covenant of Works."
Here's how the objection to this doctrine goes (which proponents of the Federal Vision never tire of voicing):
To speak of Adam's loving relationship with his Creator, or Jesus' loving relationship with his Father, as a "Pelagian brownie-point system of merit" is to reduce these familial, gracious, dynamic relationships to sterile, clinical, forensic levels. After all, both the first and second Adams were already enjoying God's favor from the very beginning, so to assume that they had to "earn" or "merit" what they were obviously already enjoying is clearly mistaken.
Plus, Adam's creaturehood made "earning" even the smallest blessing from his Creator impossible (even before the fall); since man can never bring the Almighty into his debt, all that we have is necessarily a gift of grace.
And furthermore, there is such a "disproportionality" between the requirement ("If you don't eat an apple...") and the reward ("... you'll earn eternal life!") that to speak of "merit" in this connection is silly. Doesn't Jesus teach us to say, after we've done our duties, that we are still "unprofitable servants" (Luke 17:10)?
Are these arguments strong? Weak? Why?